[SPARK-28623][SQL] Support dow, isodow and doy by extract()

[MaxGekk]

What changes were proposed in this pull request?

In the PR, I propose to use existing expressions DayOfYear, WeekDay and DayOfWeek, and support additional parameters of extract() for feature parity with PostgreSQL (https://www.postgresql.org/docs/11/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT):

1. dow - the day of the week as Sunday (0) to Saturday (6)
2. isodow - the day of the week as Monday (1) to Sunday (7)
3. doy - the day of the year (1 - 365/366)

Here are examples:

spark-sql> SELECT EXTRACT(DOW FROM TIMESTAMP '2001-02-16 20:38:40');
5
spark-sql> SELECT EXTRACT(ISODOW FROM TIMESTAMP '2001-02-18 20:38:40');
7
spark-sql> SELECT EXTRACT(DOY FROM TIMESTAMP '2001-02-16 20:38:40');
47

How was this patch tested?

Updated extract.sql.

[SparkQA]

Test build #108711 has finished for PR 25367 at commit ef3552b.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[dongjoon-hyun]

+1, LGTM. Merged to master.
Thank you, @MaxGekk !

[cloud-fan]

It's very confusing that DOW returns different results from DAYOFWEEK. DOW should just be an abbreviation of DAYOFWEEK. See also https://docs.snowflake.com/en/sql-reference/functions-date-time.html#label-supported-date-time-parts

Do we have a clear document about what these names mean? cc @HyukjinKwon @maropu @wangyum

[MaxGekk]

Here we just follow PostgreSQL definition of DOW, see:

dow
The day of the week as Sunday (0) to Saturday (6)

SELECT EXTRACT(DOW FROM TIMESTAMP '2001-02-16 20:38:40');
Result: 5

Do you propose to break compatibility with PostgreSQL?

[cloud-fan]

We never promise pgsql compatibility and internal consistency is much more important for Spark.

For this case, I think the behavior of DOW from pgsql is correct and commonly used by other databases. We should fix our DAYOFWEEK instead.

[maropu]

Do we have a clear document about what these names mean? cc @HyukjinKwon @maropu @wangyum

Currently, we just list up these names in ExpressionDescription of DatePart: https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeExpressions.scala#L2124
If we add ExpressionDescription for EXTRACT, the list will appear for EXTRACT, too, in the Built-in Functions document for Spark 3.0. If we need to describe more about these parameters, I think we need to update the argument section there.

[dongjoon-hyun]

BTW, @cloud-fan . DAYOFWEEK is added two years ago. (#21479)

We should fix our DAYOFWEEK instead.

cc @marmbrus and @gatorsmile since the request might mean a behavior change.